If by virusblocker you mean any program which will help protect your server against viruses... I do not believe this is on DirectAdmins todo list at this time since you can implement it on your own (and is something you should do as such anyway).
There is a howto on these forums and I'm sure it can be found with the search function.
If your reffering to an actual program named "virusblocker", then I am not aware of it, my bad.